The game features 3 console-exclusive characters. The Gamecube version features Link from The Legend of Zelda: Ocarina of Time. The Playstation 2 version features Heihachi Mishima from the Tekken series. The XBox version features the Todd McFarlane creation Spawn.
Link, the protagonist of Nintendo's Legend of Zelda series and the special character exclusive to the Nintendo Gamecube version, is known for never actually speaking in the Zelda games. Thus, all of his "dialogue" in Soul Calibur II is simply a collection of yells and other exhertion sounds performed by Nobuyuki Hiyama, who also provided the Japanese voices for Nightmare and Yoshimitsu. His voice work for Link is used in both the Japanese and English voice collections.
Not only was Todd McFarlane's Spawn used in the game, but McFarlane also designed Necrid, a console-exclusive character featured in all versions of the game.
Two of the unlockable hidden characters in the home versions of Soul Calibur II, Berserker and Assassin, are generic characters that use the moves and fighting styles of a pair of characters from the previous games in the series, Rock and Hwang.
One of the new characters, Cassandra, is the lead character of an old Namco video game series from 1986-1990 called "Valkyrie no Densetsu" (Valkyrie's Legend). Though known as Walkyure previously, later in the series, she was also known as Cassandra Walkyure.